As of latest version (2.5.16), youtube’s official mobile app gives you the opportunity to play any video on any Youtube capable device . You just need to be logged in to Youtube on your mobile and on your TV or PC or whatever.
If your devices are paired, you should see the remote play icon on your mobile app. Press it and the video will start playing on the other device. In less words this is a Youtube remote.
Go to youtube.com/leanback and click on that play remotely icon to pair your devices.
Also, with this latest update, videos won’t play in HQ on my mobile phone. I did select “play HQ when available” in the settings menu, but nothing happened. maybe it’s me, maybe it’s Jewtube